Lm automobileEnggLab

Systems of engine lubrication

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Auto-Lab-Manual

Splash system
Pressure system

Systems of engine lubrication
The various systems adopted for the lubrication of automobile engine are
1
Petroil system
Splash system
2 Pressure system
3 Dry sump system

Petroil system
This is used generally for small two stroke engines, e.g. in majority of scooter and motorcycle engines. It is the simplest of all types of engine lubrication systems. Certain amount of the lubricating oil is mixed with the petrol itself, the usual ratio being 2% to 3% of oil. If it is less, there is danger of oil starvation or insufficient lubrication causing damage to the engine if however, it is more, there will be excessive carbon deposits in the cylinder head and the engine will also give dark smoke. When the petrol mixture enters the crankcase, due to high temperatures there, the petrol component vaporizes leaving a thin film of lubricating oil on the crankcase, cylinder walls, crankshaft and bearings. The main requirements of lubricating oil for two stroke engine are that it should readily mix with petrol and burn without leaving much residue.
Splash system
This was employed for the engines of early motorcycles. It is one of the cheapest methods of engine lubrication. A scoop is made in the lowest part of the connecting rod and the oil is stored in the oil trough (fig) it being pumped therefrom the crankcase oil sump. When the engine runs the scoop causes the oil to splash on

the cylinder walls each time it passes through its BDC position. This affects the lubrication of engine walls, gudgeon pin, main crankshaft bearings, big end bearings etc.
Pressure system This system is used almost universally in modern car engines. The splash system though cheaper, is not suitable for automobile engines because of the absence of positive lubrication. In the pressure system (fig ) an oil pump takes the oil from the wet sump through a strainer and delivers it through a filter to the main oil gallery at a pressure of 200 to 400 kPa. The oil pressure is controlled by means of a pressure relief valve, situated in the filter unit or the pump housing.

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